Short Answer 
The answer explains that allusion is a literary device that enhances understanding by referencing ideas indirectly. The phoenix symbolizes rebirth and regeneration, reflecting the continuous cycle of life and death in nature, where death fosters new growth and renewal.
Step 1: Understanding Allusion
Allusion is a literary device that involves referencing something indirectly through creative language. This technique allows writers to evoke ideas and emotions without stating them explicitly. In literature, this can deepen the reader’s understanding and connection to the themes being explored.
Step 2: The Phoenix as a Symbol
In the context of the poem, the phoenix serves as a powerful symbol of rebirth and regeneration. The imagery of the phoenix rising from its ashes represents the concept of life after death. This symbolism connects to the broader theme of how nature constantly evolves and renews itself.
Step 3: The Cycle of Life in Nature
The theme suggested by the phoenix alludes to the *continuous cycle of life and death* in nature. When elements of nature perish, they pave the way for new growth, highlighting the vibrancy of life. This cycle can be summarized as follows:
- Death leads to transformation.
- New life emerges from what has passed away.
- Nature is an ongoing process of renewal and resilience.